diff --git a/sys/targets/targets.go b/sys/targets/targets.go
index e1c763f42e7a..69b530a94417 100644
--- a/sys/targets/targets.go
+++ b/sys/targets/targets.go
@@ -782,6 +782,13 @@ func initTarget(target *Target, OS, arch string) {
 
 func (target *Target) defaultDataOffset() uint64 {
 	if target.PtrSize == 8 {
+		if target.VMArch == ARM64 {
+			// On ARM64, in many cases we can't use many enough bits of the address space.
+			// Let's use the old value for now. It's also problematic (see #5770), but it's
+			// lesser of the two evils.
+			return 0x20000000
+		}
+
 		// An address from ASAN's 64-bit HighMem area.
 		// 0x400000000000 works both for arm64 and amd64. We don't run syzkaller tests on any other platform.
 		// During real fuzzing, we don't build with ASAN, so the address should not matter much as long as